A periodontal disease is a multifactorial disease affected by causative factors, environments, hosts, etc. Typically, a periodontal disease is a disease induced by periodontal pathogens, and is a disease developed in periodontal tissues consisting of gingiva, periodontal membrane, cementum and alveolar bones that support teeth. Development of the symptom causes severe connective tissue destruction (inflammation) in epithelial attachment, gingival connective tissues and periodontal membrane, and is accompanied by absorption of alveolar bones that support teeth, resulting in loss of teeth. Medicinal components such as tranexamic acid, allantoin, ε-aminocaproic acid, lysozyme, sodium chloride, dihydrocholesterol and β-glycyrrhetinic acid are used for prevention and treatment of such diseases by targeting local action factors and aiming at bactericidal effect of periodontal pathogens, improvement of blood flow in periodontal tissues, tissue activation, improvement of inflammation and prevention of bleeding. Further, nonsteroidal antiinflammatory agents such as flurbiprofen (J. Periodont. Res., 23, p. 166-169, 1988) and indomethacin (J. Periodont. Res., 17, p. 90-100, 1982) have been reported to be effective. Further, JP-A-60-61524 describes that ibuprofen and flurbiprofen have suppressive effect against alveolar absorption. However, periodontal pathogens in periodontal disease lesions have resistant activities to bactericides and antibacterial agents by forming a biofilm, and preventive and therapeutic effects against periodontal disease are insufficient even when using such pharmaceutical components (The Quintessence, Vol. 16, No. 11, p. 2629-2640, 1997).
So far, antibacterial agents have been considered useful with the expectation that these agents will continually be stable in the oral cavity for a long period of time (JP-A-02-288819). However, these agents are known to have a poor anti-inflammatory effect on gingival, because their effect is prone to weaken due to the formation of biofilm, as well as because these agents' activity is confined to bactericidal effect against periodontal disease pathogens and therefore cannot extend to the nascent region of such pathogens. As a result, these agents remain insufficient as an agent for the prevention and treatment of periodontal disease.
With an objective to prevent and treat periodontal diseases, polyphenols have been examined as edible plant extracts from the standpoint of safety. Examples thereof include a composition containing tea extract for anti-caries and anti-periodontal diseases (JP-A-01-90124), allergy suppressive agents, anti-caries agents and a deodorizer containing fruit juice that includes fruit polyphenols (JP-A-07-285876), anti-caries materials containing hop polyphenols (JP-A-01-90124), a food composition and a composition for oral application to prevent or treat periodontal disease containing grape seed extract, vitamin C and vitamin E (JP-A-2002-29953) and effect of strips containing 5% green tea catechin on improving periodontal diseases (J. Periodont. Res., 37, p. 433-438, 2002). However, these have a number of disadvantages such as insufficient preventive and therapeutic effects for periodontal diseases and strong astringency caused by a high content of polyphenol.
There are reports that specific naphthalene derivatives (lignans) and plant extracts of Berberidaceae Podophyllum, Umbelliferae Notopterygium and Cupressaceae Thujopsis containing the same have preventive and therapeutic effects for osteopathy (JP-A-06-340528 and JP-A-06-340542) and asunaro (Thujopsis dolabrata) extract has suppressive effects for cell adhesion (JP-A-09-315991); however, no anti-inflammatory effect in gingiva where biofilm is present is known.
Further, it is known that the extract of Thujopsis plants exhibits antibacterial action against Streptococcus mutans, which is a causative pathogen of dental caries (JP-A-63-238014); however, no preventive and therapeutic effect for periodontal disease is known.